How to Do Sit-ups the Right Way, According to Personal Trainers

As you go about your business in the weight room, have you ever glanced over at a personal trainer during one of their client sessions and idly asked yourself something like, Dang, I wonder if they ever happen to notice what I'm doing over here? Good news! While your gym's fitness professionals obviously can't leave their charges to deliver you some kind of stern pro bono talking-to, they do see you, and they have a lot of feelings to share about... all the myriad things you're doing wrong. (Perhaps this is, in retrospect, one of those questions to which you didn't want to know the answer.)

Fortunately, a few trainers have generously agreed to share with us the most common and most aggravating habits they see gymgoers developing—and a little free advice on how to fix them. This is, in effect, money in your pocket. Today: sit-ups.

The air up there

Grounded sit-ups and crunches are fine, but I prefer doing ab exercises while hanging from a pull-up bar, because the simple act of raising your knees as high as you can towards the chin demands tremendous core strength and stability. (In a sit-up, the ground stabilizes you, but when you're hanging in mid-air... nothing stabilizes you.) Hanging abdominal exercises recruit more stabilizer muscles, which equates to more of the results you want. Try adding a twist at the top to recruit the obliques, or just stick with the good ol' toes-to-bar. Just remember: No swinging. —Ben Booker, Second Chance Fitness

Flex those feet

Foot position might seem unrelated to getting an ab workout. It's not. The abs are part of the anterior kinetic chain that runs up and down your body, which means that engaging the quads helps to activate the abs, too. Ankle dorsiflexion—the motion of your feet when you lift the balls of your feet off the ground—is the easiest way to accomplish that. For example, many people perform exercises like the Russian twist with their knees slightly bent and their feet extended naturally. Get the rest of that kinetic chain involved by flexing your feet and straightening your legs. —Devan Kline, Burn Boot Camp

Momentum shift

Because people tend to do more reps of crunches than, say, bench press or squat, there's a tendency to hurry through each set. When you do that, you're going to start relying on momentum to propel your torso instead of using your abs. This is bad. Be sure you're performing each rep in a slow, controlled manner. (Like you do with, say, bench press or squat.) Focus on bringing your ribs down towards your belly button at the top, and after each rep, pause and press your back firmly against the floor to prevent yourself from bouncing off of it. —Idalis Velazquez, IV Fitness

Everything is connected

Everyone wants to see results in the midsection, but too many gymgoers are straining to achieve that goal with standard crunches, which are one of the least effective exercises for eliciting change. Focus on sit-up varieties that require engagement of the full body, including the legs—decline bench crunches, straight-legged crunches, crunches using dumbbells, bicycle crunches, and the like. Trying to get a six-pack with crunches alone, where you're just bobbing the torso up and down, is like trying to improve your car's engine by replacing the hood. (Don't try to improve your car's engine by replacing the hood.) —Josh Cox, Anytime Fitness